Arrangement for bridging an electric circuit



March 29, 1960 P. WALDVOGEL ARRANGEMENT FOR BRIDGING AN ELECTRIC CIRCUIT Filed Sept. 25. 1957 ATTORNEYS United States Patent ARRANGEMENT FOR BRIDGING AN ELECTRIC CIRCUIT Application September 25, 1957, Serial No. 686,256

Claims priority, application Switzerland September 26, 1956 8 Claims. (Cl. 200148) In electrical systems, it is often necessary to provide temporary bridging between component parts of the system having difierent potentials. For example, it has been proposed, in order to take off abnormally high capacitative charges and induced potentials from a phase conductor of a high potential transmission line, to temporarily establish a bridge between the conductor and ground.

Heretofore, it has been known to utilize for such bridging purposes a grounding disconnect switch or a power disconnect switch. However, when grounding disconnect switches are used they must be switched on and off with great speed in order to restore the line conductor to its normal operating potential with a minimum of no-potential interval. This requirement for great switching speed necessitates large forces for imparting the necessary accelerating forces to the switch contacts since the latter have considerable mass. Also, in applications to very high voltage installations, the switching time is longer than desirable. Power disconnect switches do not have the disadvantage of the grounding type disconnect switch but the former are considerably more expensive and hence make the system less economical.

It has also been known to use a jet of liquid such as electrically conductive water for temporarily establishing an electrical bridge so as to temporarily ground a system, or for overvoltage arrester applications, but in the known arrangements a principal disadvantage was the relatively long time required to effect the liquid bridge, especially in cases involving high potentials where the distance to be bridged is necessarily quite long in order to prevent accidental flashovers between the conductors and ground. Moreover, even where the liquid bridging jet could be established it has not been possible, especially in cases where relatively large amplitude currents are involved, to satisfactorily extinguish the current flowing through the jet.

The object of the present invention is to provide an improved arrangement wherein the disadvantages of the prior known techniques are eliminated. The bridging time is reduced by the fact that compressed gas such as air is used toforce a jet of conductive liquid such as water from a container so as to strike with minimum time delay against a counter electrode. Moreover, by appropriate design of the counter electrode, the liquid jet striking against the same is caused to be divided and atomized thus minimizing the danger of flashovers causing difficulty by the liquid as it falls back. A further advantage inherent in the invention is that the compressed air, in addition to causing the bridging conductive liquid jet to be hurled with great velocity against the counter electrode, is continued after the supply of liquid is exhausted and serves to thereafter extinguish the are formed between the electrodes.

The invention will become more apparent from the following detailed description of various practical embgldirlrlients thereof and, the accompanying drawings in w 1c "ice Fig. l is a vertical view of one embodiment with some parts being shown in central section and others in elevation;

Fig. 2 is a view in central vertical section of one modification of the liquid container unit shown in Fig. l; and

Fig. 3 is also a view in central vertical section of another modification for the liquid container unit shown in Fig. 1. I

With reference now to the drawings and to Fig. 1 in particular, it will be seen that a container 1 made of electrically conductive material is provided for the liquid circuit bridging agent 2, such liquid being preferably water in view of its low cost, and which has been rendered electrically conductive by the addition thereto of any suitable agent such as sodium carbonate. Also, in winter, especially in the case of outdoor installations, a suitable anti-freeze agent such as alcohol, should be added to the water to prevent freezing.

Located centrally of the container 1 at the bottom thereof is an inlet 3 for compressed air controlled by a valve 4 which can be actuated directly or remotely through conventional solenoid actuating means, not illustrated. The compressed air is supplied constantly to the inlet 3 from a suitable source, also not illustrated.

Also located centrally of the container 1 at the top thereof is an outlet aperture 5 in which is situated an upwardly pointing preferably conically shaped nozzle or electrode 6. The supply of water to container 1 is through an inlet pipe 7 controlled by a valve 8 which, like the air control valve 4, can be actuated remotely by the provision of solenoid actuating means.

The container 1 which stands upon legs 9 can rest upon the ground directly or it can be supported upon a platform 10. The electrode 6 is, of course, electrically connected to one part of the circuit to be bridged, and such part can be ground, as illustrated schematically.

Supported vertically above the electrode 6 and spaced therefrom by a substantial air gap is another electrode 11 to and depend from an overhead suspended high voltage conductor.

Operation of the arrangement shown in Fig. 1 is as follows. The container 1 is normally in a liquid filled condition. When it is desired to effect a bridge between the high voltage conductor 12 and ground, the air valve 4 is opened and the entering compressed air forces the liquid upwardly through the container outlet aperture 5, the liquid being divided as it flows past the conically shaped electrode 6. The upwardly hurled liquid stream strikes the counter electrode 11, and since the latter has a wedge-shaped configuration, the liquid upon striking the electrode surfaces is atomized and flows off to both sides in opposite directions. When all of the liquid 2 has been ejected from container 1, the compressed air continues to flow and is thus able to extinguish the are formed between the electrodes 6 and 11 by the bridging column of liquid. The wedge-shape for the counter electrode 11 is preferably selected in order to minimize the danger of flashover caused by the return downward flow of the liquid. The wedge shape not only divides the liquid stream or jet into two parts but also causes such parts to be atomized as they strike the inclined surfaces of the electrode. In order to increase the atomizing effect, the surfaces of electrode 11 can be roughened.

In the modified embodiment illustrated in Fig. 2, the container is shown at 1', the liquid therein at 2', the inlet for compressed air at 3', the air valve at 4', the

' outlet aperture at 5', the conical electrode at 6', the liquid'inlet pipe at 7 and the liquid control valve at '8'. The elements so far enumerated are similar in construction to the corresponding components in the embodiment shown in Fig. 1 and hence have been assigned like reference numerals but with single primes appended for purposes of distinction. In this embodiment, instead of the compressed air being applied directly against the body of the liquid in the container 1', a piston arrangement is used, it being seen from the drawing that a piston 15 is disposed in the lower portion of the container 1"which serves also as a piston cylinder and that the compressed air admitted through inlet 3 and valve 4' is applied against the lower face of piston 15 thus pushing the piston upward and forcing the liquid upwardly and outwardly through the discharge aperture 5'. In order to permit the bridging column of conductive liquid to be followed by compressed air for extinguishing the arc formed between electrodes 6' and 11 by the electrical bridge, it will be seen that container 1' is provided at the upper portion thereof with a by-pass 16 which permits the compressed air to flow around and hence bypass the piston 15 after the latter has been moved to the position indicated by the dotted lines and stopped by engagement with the lower face of the electrode 6. Inparticular, when piston 15 reaches the dotted line p- SlilOll in engagement with electrode 6', it will have been raised sufiiciently high to uncover the by-pass inlet port 16a from container 1 and also the by-pass outlet port 16!) back into the container 1' above piston 15. Thus compressed air passes from the under face of raised piston 15 in container 1 into inlet port 16a, through the bypass 16, and thence out through outlet port 16b into container 1' above the upper face of piston 15 and thence outwardly through the outlet aperture to extinguish the are formed between electrodes 6 and 11.

The other modification illustrated in Fig. 3 also includes a piston arrangement as in the embodiment of Fig. 2, but the piston structure itself is somewhat different, there being a first piston for forcing the conductive liquid out of the container and a second piston integrated w1th the first piston against which the compressed air is applied for driving the combined first and second pis tons upward. With reference now to Fig. 3, the contalner structure for the liquid is, in several respects, similar to the embodiment illustrated in Fig. 1 and hence corresponding components have been assigned similar reference numerals but with double primes appended for purposes of distinction. Disposed in the lower portion of container 1" is a first annular piston 17 the function of which is to force the liquid 2" upwardly through the outlet or discharge aperture 5". Extending downwardly from piston 17 is a tubular connecting portion 18 of reduced diameter and the latter terminates in a second annular piston I? which is arranged for sliding vertical displacement in a cylinder 26. The lower portion of cylinder 20 beneath piston 1% includes a compressed air inlet 21 controlled by a valve '22. Arranged within the tubular connecting portion 18 is a control valve consisting of an elongated valve stem 23a guided for longitudinal sliding movement in the tubular portion 18, havmg at its upper end a contact member 23b adapted to engage and be stopped by the under face of electrode 6", and having at its lower end a plate 23c which is of sufiicient area to block off the passageway 24 through pistons 17, 1.9 and the tubular connecting portion 18. The cross sectional area of piston 17 is greater than that of piston 19 in order that valve plate 23c will remain firmly pressed against the under face of piston 19. Operation of the Fig. 3 embodiment is as follows. T he component parts normally occupy the positions indicated in the drawing just prior to the electrical sna ing operation. When it is desired to establish the bridge, compressed air control valve 22 is opened thus admitting air to the under face of piston 19 and forcing valve plate 230 against the under face of piston 19 thus closing off any air through passageway'24. The compressed air then forces piston 19 and valve plate 230 upward together which thereby also forces piston 1'7 upward to discharge the bridging liquid 2" from the aperture 5". When the contact member 23b of valve 23 strikes the under side of electrode 6", its movement will be stopped. However, pistons 17 and 19 continue their upward movemerit thus causing the valve plate 23c to separatefrom the under face of piston 19 and permit compressed air to flow upwardly through passageway 24 and the central aperture in the annular piston 17 and out of the discharge aperture 5 from the container thus extinguishing the arc formed by the electrically bridging liquid column between electrodes 6" and 11.

' In conclusion it will be understood that I have provided an improved temporary electrical bridge of the liquid column type which is established by application of compressed gas, such as air, to a supply of conductive liquid such as water in a container, the compressed air causing the liquid to be forced upward in a column or jet through a discharge aperture in the container provided with an electrode to strike a counter electrode attached to a high voltage conductor, the temporary liquid bridge then being broken when the liquid supply in the container has been exhausted, and the arc established between the electrodes by the liquid bridge being extinguished by continuing the flow of the compressed air in the same direction as the water jet after the supply of liquid in the container has been exhausted. Moreover, the electrode against which the jet of liquid impinges is so constructed that impact thereon by the jet causes the liquid to be atomized thus minimizing the establishment of flashovers that could be caused by the liquid as it falls back down by gravity.

The duration of the liquid bridge will depend upon the quantity of liquid in the container and hence can be varied by varying the'volumetric capacity of the container. Moreover, the duration of'the temporary liquid bridge can be varied by the magnitude of the air pressure. The bridging must persist until a faulty current flowing on the high voltage conductor has been commuted into the bridging. Since this differs with different types of conductors, adjustability of the current transfer is desirable and can be achieved as previously indicated by appropriate adjustment of the quantity of liquid hurled upward in the jet or of the air pressure.

The inventive concept can be applied as shown in the presently illustrated embodiment for single pole, short time disconnection purposes, the high voltage conductor being connected to ground briefly through the liquid jet. If the inventive concept is applied under circumstances where very high currents must flow across the bridge, for example in bridging series connected condensers which are connected to a high voltage transmission line in order to effect a compensation for line inductance, several of the arrangements as shown in the drawings can be arranged in parallel so as to establish simultaneously a plurality of bridging liquid jets which thereby divide the current between them.

When the invention is used for bridging series connected condensers, both electrodes must be connected to voltage. The liquid jet must continue to bridge until the protective devices on the transmission line have deenergized the high voltage line conductor in the proper manner or the line has been restored to normal conditions by other means. In such application the series condensers are, as a rule, bridged by spark gaps which, in the case of a line fault, respond instantaneously due to the voltage rise between the condenser terminals. To relieve this as soon' as possible, a liquid bridging switch according to the present invention is then connected in parallel.

In conclusion .it will be understood that while several practical embodiments of the invention have been described and illustrated various departures therefrom in structure may be resorted to without, however, departing from the spirit and scope of the inventive concept as defined in the appended claims. I

I claim:

1. The methodrof effecting a temporary bridge for an electrical circuit comprising the steps of hurling a predetermined quantity of electrically conductive liquid in the form of a jet by means of compressed gas from a near to a far bridging point so as to establish an arc between said points, atomizing the liquid jet as it strikes the far bridging point and continuing the flow of compressed gas in the direction of said far bridging point after said liquid jet has terminated to thereby extinguish with the compressed gas the are formed between said bridging points.

2. Apparatus for eifecting a temporary bridge for an electrical circuit comprising a container adapted to be at least partly filled with an electrically conductive liquid, said container having an aperture for discharging said liquid in a generally vertical upward direction, an electrode associated with said aperture, 2. counter electrode arranged in vertical spaced relation from said electrode and in the path of the liquid ejected from said container through the discharge aperture therein, and means for supplying compressed gas into said container for forcing the liquid outwardly and upwardly through said discharge aperture in the form of a jet which bridges said electrodes, said supply of gas being continued and discharged through said aperture in the direction of said counter electrode after the liquid in said container has been exhausted thereby to extinguish the are formed between said electrodes.

3. Apparatus as defined in claim 2 wherein said counter electrode is wedge-shaped to provide inclined faces presented to said liquid jet impinging thereupon and which divides said jet into two streams which the atomized upon impingement.

4. Apparatus as defined in claim 3 wherein said inclined faces of said counter electrode are roughened to promote the atomizing action.

5. Apparatus as defined in claim 2. wherein said container includes a piston slidably arranged therein in spaced relation to said discharge aperture and with the electrically conductive, liquid therebetween, and means for I applying said compressed gas to said piston so as to force said piston to slide in the direction of said discharge aperture.

6. Apparatus as defined in claim 5 wherein said container includes a by-pass around said piston through which said compressed gas can flow to said discharge aperture after said piston has been moved to the point where substantially all of said liquid has been discharged from said container.

7. Apparatus for effecting a temporary bridge for an electrical circuit comprising a container adapted to be at least partly filled with an electrically conductive liquid, said container having an aperture for discharging said liquid in a generally vertical upward direction, an electrode associated with said aperture, 2. counter electrode arranged in vertical spaced relation from said electrode and in the path of the liquid ejected from said container through the discharge aperture therein, a first piston slidably arranged in said container in spaced relation to said discharge aperture and with said electrically conductive liquid therebetween, a second piston located below said first piston and connected thereto by a member having a longitudinal passageway therethrough and through said pistons, a cylinder receiving said second piston, valve controlled means for admitting compressed gas into said cylinder below said second piston for forcing said pistons upwardly thereby to cause said liquid to be ejected upwardly through said discharge aperture in said container, and second valve means controlling said passageway through said connecting member and pistons, said second valve means being closed to block 01f said passageway during the water ejecting phase of piston movement, and means controlled by upward movement of said pistons to effect opening of said second valve means thereby to cause said compressed gas to flow upwardly through said passageway and pistons frornsaid cylinder into said container and outwardly through the discharge aperture therein to extinguish the are formed between said electrodes.

8. Apparatus as defined in claim 7 wherein the cross sectional area of said first piston is larger than that of said second piston and said valve means comprises a valve plate covering said passageway at said second piston and a valve stem adapted to engage and be stopped by said electrode.

References Cited in the file of this patent UNITED STATES PATENTS 520,776 Gibboney June 5, 1894 890,679 Merriam June 16, 1908 991,483 Creighton May 9, 1911 1,061,671 Hilliard May 13, 1913 FOREIGN PATENTS 223,461 Germany June 21, 1910 

